Dental treatments are mostly performed through the use of various drilling buns, also termed dental burrs, which penetrate tissue structures, such as tooth enamel and dentin, as well as bone and soft tissue. Such dental burrs are mainly used for cutting through the tissue structure, and shaping and polishing restorations materials. Sharp burrs ensure fast working time, less pain to the patient and lower vibration sensation.
Most buns are intended for multiple uses and are sterilized between patients. However, the burrs tend to wear after repeated use. Replacing the bun during a dental procedure is time consuming and bothering, for both patient and dentist. In addition, it is difficult to assess when a bun should be replaced.
Additional dental instruments that are intended for multiple uses and tend to wear include dental scalers, including ultrasonic dental scalers, implant drills, curettes, probes and explorers.
For example, during clinical procedures, ultrasonic scaler tips may become worn and reduced in length. Tip wear could affect the performance of dental ultrasonic scaler inserts by reducing their vibration displacement amplitude (see, for example, Lea et al. (2006) J Clin Periodontol., 33(1):37-41). In addition, it has been reported that cavitational activity occurs in distinct areas along the length of the ultrasonic scaling tip, which is powerful enough to produce wear of the metallic surface (Lea et al. (2008) Dental Health, 47; 5-8).
As another example, it has been shown that used implant drills cause an increase in bone temperature during osteotomy (see, for example, Chacon et al. (2006) J Oral Maxillofac Surg., 64(2):265-9). The rise in bone temperature has a negative impact on bone tissue and the outcome of the implant procedure. Using a proper implant drill may decrease bone temperature rise during osteotomy, thus reducing thermal injury.
As a further example, dental explorers and probes, which are routinely used during dental examination for identification of caries, may become dull. A dull explorer tip may result in false-negative diagnosis.
As a further example, repeated use of instruments such as scalers and curettes wears away minute particles of metal from the blade, causing their edge to take on a rounded shape resulting in a dull, ineffective blade. Scaling and root planing are most effective when using sharp instruments. When the blade is dull, a clinician may lose the ability to “feel” the sharp edge “grabbing” onto a surface. It may then seem that the blade is sliding over the surface or deposit, which causes the clinician to work harder to remove deposits. This may result in burnishing rather than removing the deposit.
Thus, there is a need to determine the condition of dental instruments and the level of wear prior to or during their operation.
A common suggested method to determine sharpness of various dental tools is by using the Hard Plastic Test Stick. In this test, the sharpness of an instrument is measured by gliding it on the test stick. A sharp edge will “grab” the test stick and the test stick will produce a metallic clicking sound. A dull edge will slip or slide over the surface of the test stick. Another common way to test the sharpness of an instrument is to inspect the blade visually.
U.S. Pat. No. 5,208,761 discloses a method for the confirmation of the diameters of plural drills of different diameters in a PWB (printed wiring board) working machine in which the drills are interchangeably mounted to perform drilling The method comprises storing, with respect to each of the drills, data on whether or not the drill has already been used, checking the data of one of the drills upon drill replacement, and measuring the diameter of the drill only where the drill has not previously been used.
U.S. Pat. No. 6,877,984 discloses a device for cleaning endodontic files and indicating flaws in endodontic files comprising a foam core contained in a housing and a covering overlaying the core through which a file is inserted into the device. A method for cleaning endodontic files using the device comprises the steps of inserting a file into the device and withdrawing the file. A method for detecting flaws in a file, includes the steps for cleaning the file and then examining the file for debris from the endodontic procedure adhering to the file which indicates the presence and location of damage to the file.
US 2006/0286506 discloses a method of making and using a dental tool that is recommended to be reused a certain number of times, with markings on the shaft of the tool that correspond in number to the number of recommended uses of the tool. A visually perceptible marking, such as paint or ink may be applied to annular recesses or to a portion of the shaft surface that is not recessed. One of the markings is removed from the shaft of the tool prior to reusing the tool. The dental tool disclosed in US 2006/0286506 has a cutting element and a shaft that is provided with a plurality of deposits or indicators applied to the shaft.
US 2009/0129882 relates to methods, systems, and devices for monitoring tool breakage and wear in a dental milling machine. US 2009/0129882 discloses, inter alia, a dental milling system which includes a milling tool for milling a dental prosthetic and a spindle operable to receive, fixedly engage, and rotate the milling tool. A first accelerometer is positioned adjacent to the spindle and is operable to detect vibrations associated with rotation of the milling tool. A processor is in communication with the first accelerometer to receive data sets representative of the vibrations detected by the first accelerometer. The processor processes the data sets to identify changes in one or more harmonics of the detected vibrations indicative of a break of the milling tool.
US 2009/0322541 discloses a performance sensor, and more particularly, a performance sensor for a handheld dental drill. Operation of a handpiece is sensed, such as by detecting temperature and/or vibration associated with one or more of bearing rings supporting a turbine in the hand piece. When operation exceeds a threshold, a visual or audible indication is provided, and power to the turbine may be interrupted. The sensor(s) may be built into the hand piece, or be part of a removable girdle placed on the handpiece. Typically, the hand piece is used for dental or medical applications.
There still remains a need for methods and devices that would enable a simple and accurate evaluation of the status of various mechanical instruments, particularly surgical and dental instruments, prior to or during dental or surgical procedures that may be used by the clinician or his/her assistants.